Control spring

Control feathers of a male Sparrowhawk: the outer ones above, the inner ones below.

Control feathers of a black grouse: the inner ones on the left, the outer ones on the right.

The tail feather on the tail of a bird is called a rudder feather ( rectrices ) . In the hunter's language the control springs are called shock .

The length of the control feathers in relation to the shape of the wings is an essential feature in the flight pattern and allows conclusions to be drawn about the flight behavior of a bird. The rudder, as the summary of the control springs is called, can have several functions:

• Control in flight;
• Balance in sitting and walking;
• Support when climbing ( woodpeckers and treecreepers );
• Sound generation in courtship ( snipe );
• Signal effect through shape and color during courtship ( black grouse , peacock , lyre-tail ).

Some species have only rudimentary control feathers ( grebes ). These are usually created in pairs. Exceptions are kiwis , emus and cassowaries . Most species have six pairs, but there are also species with only four (run chickens ) or, at the other extreme, 16 pairs of tail feathers ( bulwer pheasant or crowned pigeon ).

The pictures clearly show how the ratio of the width of the inside to outside flag changes from inside to outside.

literature

• Wolf-Dieter Busching: Handbook of the plumage of European birds . AULA-Verlag, Wiesbaden 1997, ISBN 3-89104-570-0